Metering dispenser

ABSTRACT

For a cost-effective design of a metering dispenser for dispensing a substance ( 12 ), which is poured into a container ( 1 ) that is open at an end face and which can be removed from the container ( 1 ) by means of a pump unit ( 10 ), wherein a piston ( 5 ) is inserted in the container ( 1 ), the piston ( 5 ) has smaller dimensions than the inner contour of the container ( 1 ) and a film ( 5   a ) of the pasty substance ( 12 ) is provided in order to seal between the piston ( 5 ) and the inner contour of the container ( 1 ).

The invention relates to a dispenser with the pre-characterizing features of claim 1.

The prior art discloses dispensers with trailing piston systems. They consist of a metering dispenser pump and each pump is associated with a round or oval cylindrical container which is closed airproof on the bottom by a level corresponding entrained piston. The container is filled with the substance without air inclusions. When dispensing, the pump sucks out the component from the container, and due to the resulting negative pressure, the piston is sealed.

This trailing piston systems have been proven in practice and have three significant advantages over ventilated systems (f.i. bottle):

-   -   I. Proper performance of the pump is always guaranteed when the         container is free of air and thus the pump is always supplied         with the substance.     -   II. By sealing the piston, the emptying is optimal as the entire         vessel wall is scraped off by the piston and thus no substance         remains on the vessel wall.     -   III. The substance is not in contact with ambient air, since no         ambient air flows into the container.

A disadvantage of this trailing piston system is, however, that the proper function sets high demands on the elements and their handling. The trailing pistons must be sealed reliably to the vessel wall and must be movable at the same time with little force respectively vacuum. This is usually performed with a sealing and a guide lip, whose properties depend partly on the material, diameter and geometry of the wall thickness. In conjunction with the container, thus a very delicate, complex system results. This system responds to leaks due to damage to the vessel wall or the piston with a malfunction, as in this case, because of the negative pressure of the pump, ambient air will be sucked into the container, instead of dragging the piston. If the frictional force to move the piston is too high, no product can be sucked by the pump due to the resulting negative pressure in the container.

When using very small diameters, the relation of circumference of the drag piston and thus the frictional resistance compared to the piston surface, which is available due to the negative pressure for movement of the piston, is extremely unfavourable. The necessary requirements of tolerances and surface finish in case of small diameters of f.i. 15 mm diameter require high precision tools for manufacturing these parts, as well as a very thorough quality assurance. This necessary precision causes high production costs and high investment.

Further, the shape of the container is very limited and only round or oval contours are technically feasible. If the drag piston is inserted after filling of the container, it is usually provided with a vent, which is then closed by a stopper, being an additional part. If there are solid particles in the substance, they can cause additional friction between the piston and the vessel wall, thus preventing proper function of the dispenser.

Therefore, it is an object of the present invention to overcome the disadvantages of the prior art and to provide a dispenser with a simple design to provide a cost-effective solution for certain substances.

According to the invention a dispenser for certain types of substances or components will be provided, namely, for pasty substances which adhere at the surface of the piston having a certain distance from the inner container wall and therefore forms a sealing film on the inner contour of the container. The pasty substance should not dry-out or oxidize in air, so that the dispenser is preferred for substances on wax or grease base, especially for lip care products.

Accordingly, the pasty substance has a relatively low viscosity. Thus, there is no exact fit of the piston required, but can be used with considerable play of about 1% in the container. By this tolerance (in mechanical engineering named as “rough tolerance”), the piston can be rapidly assembled in the container, since the piston is no longer provided with an airtight seal with respect to the ambient air, but the adhesive sealing film as pasty substance. Therefore, preferably no volatile ingredients (for example, water, alcohol etc.) should be present, as it is the case in many lip care products anyway, such that a drying of the substance or its components cannot take place.

By this “floating” principle, the piston is not hindered in its movement by frictional forces, since it always has a distance or gap to the container wall. Therefore, the pasty substance can adhere at the surface of the piston and is entrained when emptying the system. By the adhesion of the component to the container wall, the so-formed sealing film between the piston and the container wall is maintained.

In a simple case, a piston for a cylindrical container can be formed as a ball e.g. can be used as a purchased part, which preferably has a very low specific gravity, and whose diameter is slightly smaller than the inner diameter of the container. Of course, the piston can be formed in any other cross sectional contour of the container, even as angular forms, that are hardly possible with a drag piston system that is closed airtight.

Other forms of the “floating” piston as the spherical form, such as a disc should have a certain height and a guide wall or guide ribs to prevent a tilting of the piston.

If the piston is placed on the component, the trapped air can escape completely between the piston and the container wall—a vent and its closing, as in the conventional trailing piston system, is therefore not required.

If there are solid particles in the component, which are smaller than the distance between the piston and the container wall, the movement of the piston remains unimpeded—whereas in prior art piston systems, these particles can be clamped between the container wall and the piston, and thus block the piston. For sealing the piston no frictional force must be overcome, so that by actuating the pump there is no negative pressure in the container, and there will be no ambient air sucked into the system between the container and the piston.

Since the piston does not have any contact with the container, a sealing lip, as in conventional systems, is not required and can thus be carried out as a simple solid or hollow body. The tolerances between the outer diameter of the piston and the inner diameter of the container can be relatively large and thus unproblematic in the production. The surface of the container inner wall and of the piston are practically negligible, scratches and other injuries do not affect the function of the system. In contrast to the prior art, in which the surface finish of the piston and of the container is essential, the manufacture and assembly can be carried out considerably cheaper.

Preferred gap widths between piston and container wall are between 0.02 and 0.2 mm. A low gap width causes a small residual volume, because only little product in the height of the gap width is not stripped from the piston, and thus remains as a residual volume in the container. However, a very low gap width requires higher demands on the measure tolerances of container inner contour and piston outer contour.

The piston may also be liquidly performed in form of a second bottling on the substance or component with a hardening material, which then shrinks preferably by about 1-2% during curing, in order to result in a certain gap width.

An unfavourable relation between scale (friction force) and surface (force by under pressure), as it is the case with very small diameters in conventional systems cannot occur. Thus, also very small diameter container can be produced without increased expense of precision. Such small, slender container are especially required for dispenser with 2 or more components, so that for this case, the savings in production costs adds accordingly.

Following, preferred embodiments of the invention are explained in detail with reference to the drawing. The figures show in:

FIG. 1: a dosing dispenser container with a pump unit;

FIGS. 2-6: various exemplary embodiments of the piston; and

FIGS. 7-12: various examples of shapes of the container.

Using the sectional drawing in FIG. 1, first the basic concept of a metering dispenser 1 is described, which generally consists of at least one container 1 for receiving the substance or the component, especially in an oval or cylindrical extrusion moulding, a piston 5, inserted therein and a pump unit 10. There may be provided two or more of such containers in a dispenser, each with one piston and associated pump unit. Thus, adjustment of the mixture of the individual components in the containers is possible by rotating a not-shown adjusting member. In many applications, a fixed setting of the mixing ratio is sufficient, such as 50% each.

The output of the component from the respective container 1 is effected by depression of the metering dispenser head 2 of the pumping unit 10 and the coupled movement of the pump piston 4. Thus, the volume of the pump chamber 11 is reduced, such that by the resulting pressure, the spring 8 of the outlet valve is compressed and the ball 7 opens the outlet valve as the component is conveyed out of the metering dispenser head 2. During the subsequent discharge of the metering dispenser head 2 it is pushed back with the pump piston 4 into the starting position by the pump spring 9, wherein the pump chamber 11 is enlarged and the resulting negative pressure lifts the inlet valve 6, which is shown as a flexible membrane in the middle and thus opened. In this way, a portion of the component is sucked from the container 1 into the pump chamber 11 and through the reduction of the volume of the component within the container 1, the piston 5 is pulled at the same time by the adhesion to the surface of the component. If the container is empty or the component is completely conveyed out of the container 1, the piston 5 is directly below the pump unit 10.

FIG. 1 shows the initial state of the filled container 1, whereas the piston 5 is located at the open end side of the container 1. The entire volume between the piston 5 and the container 1 is filled as possible free of air in the filled state of the component or substance 12 (here indicated only in the lower region with short wavy lines). Thus, the piston 5 is in contact with the substance, wherein the piston 5 is held in place by adhesion to the component at the shown position.

The component or pasty substance is placed through the open end of the container 1 before the assembly of the piston 5, and then the piston is placed on the pasty substance or inserted into the container 1, wherein the total ambient air between the piston 5 and substance escapes by the annular gap between the piston 5 and the container 1, and thus the piston 5 has full surface contact with the facing side of the component or substance. After the first pumping strokes a sealing film 5 a is formed in the annular gap 5 a′ (here indicated by a wavy line on the left bottom), so that the loosely fitted piston 5 is perfectly sealed to the inner contour of the container 1.

FIG. 2 to FIG. 6 show different examples of embodiments of the piston 5, and are each shown in cooperation with the container 1, wherein the upper area of the figures each shows a lateral longitudinal section and the lower area of the figures shows a corresponding cross-section through the container 1 with piston 5.

FIG. 2 shows a piston 5, which consists of a loosely fitted sleeve, which is closed with a surface towards the component, wherein the sleeve together with the sealing film 5 a serves as a guide in the annular gap 5 a′. This piston has a relatively small deadweight and adheres therefore very reliable to the component or pasty substance.

FIG. 3 shows a piston 5, which consists of a solid circular cylinder, and has a sufficient cylindrical length to ensure a reliable guide to prevent tilting of the piston. This piston 5 can be produced very cheap as a part of an extrusion element, but has a relatively high deadweight and must therefore adhere very reliable to the component. The annular gap for generating the seal film 5 a can be seen, as well.

FIG. 4 shows a piston 5 as surface with added guide ribs which are arranged for example in a cross shape. FIG. 5 shows a ball as a piston 5 which is cheaply available as a purchase part. The ball can be constructed as a solid sphere of light material or as a hollow ball in the manner of a small ping-pong ball. The container top region is advantageously formed in a hemispherical shape, in order to minimize residual volume.

FIG. 6 shows a further example similar to the principle of FIG. 2, wherein the piston is adapted to the conical top of the container to keep the residual volume low.

FIG. 7 to FIG. 12 show examples of different extrusion moulding of the container 1, which can be executed in principle in all possible, slender contours, preferably as an extruded part. 

1. A dispenser for the delivery of a substance which is filled in a container being open at an end side and can be removed from the container by a pump unit, wherein a piston is inserted in the container, characterized in that the piston (5) is smaller in size than an inner contour of the container (1) and a film (5 a) of a pasty substance (12) is provided for sealing between the piston (5) and the inner contour of the container (1).
 2. Dispenser according to claim 1, characterized in that the piston (5) is a ball, inserted into a cylindrical container (1).
 3. Dispenser according to claim 1, characterized in that the piston (5) has a lateral guide wall or guide ribs.
 4. Dispenser according to claim 1, characterized in that the piston (5) is circumferentially spaced from 0.02 to 0.2 mm by an annular gap (15 a′) from an inner wall of the container (1).
 5. Dispenser according to claim 1, characterized in that the pasty substance (12) is free of volatile components
 6. Dispenser according to claim 5, characterized in that the pasty substance (12) is a lip care product or lip decoration product.
 7. Dispenser according to claim 1, characterized in that the substance (12) consists of at least 50% of oils and waxes.
 8. Dispenser according to claim 1, characterized in that the piston (5) is first applied as a liquid composition to the substance (12) and then hardens.
 9. Dispenser according to claim 8, characterized in that the piston (5) shrinks about 1 to 2% as it hardens. 